The occupant restraint belt systems which vehicles are equipped with by the manufacturer are unsuited for use by small children. Accordingly, a variety of special child restraint systems are available and in widespread use. The most common type of child restraint system is a special seat which rests on the vehicle seat and is suitably fastened in place by either the vehicle restraint belt or a special belt. Conventional child safety seats usually consist of a small plastic shell-type seat having a padded cover and fitted with a restraint belt system composed of a pair of shoulder belts, a waist belt and a crotch belt. Because children vary considerably in size as they grow from infancy, the belts are usually adjustable. Many of the known belt systems are relatively complicated because of the number of belt sections involved and the adjustable features incorporated in them. They are also frequently cumbersome to put on the child. The child safety seats described and shown in U.S. Pat. Nos. 3,596,968, 3,606,453, and 3,794,379 are representative.
It has also been previously proposed to include an abdominal pad in the restraint belt system of the child seat. Such a pad enhances the protection of the child by spreading the load over the child's pelvic area. Examples of such systems are described and shown in U.S. Pat. Nos. 3,912,328, 4,025,111 and 4,040,664. Those systems consist of a pair of shoulder straps joined to the abdominal pad by a metal anchor member which in turn joins the shoulder straps to a crotch strap that is fastened to a buckle under the front portion of the seat. Compared to a number of other systems, which are somewhat more complex, the last mentioned systems are comparatively convenient to use, once relatively complicated adjustments have been made so that the system fits the child. On the other hand, the flexible crotch strap and the location of the buckle and buckle tongue are somewhat inconvenient to fasten and unfasten.
The present inventor has heretofore made a desirable improvement in child safety seats, and the seats embodying such improvements have been marketed in Japan for some time. One such improvement is the provision of an emergency locking retractor attached to the underside of the seat and receiving a retractor belt which is joined to a pair of shoulder belts. The provision of a retractor in the restraint belt system of the child seat has the advantages of facilitating the proper fitting of the belt to children of various sizes without requiring adjustment--the belt automatically adjusts in length--and of being more comfortable to the child by allowing him or her to move about in the seat, particularly to lean forward. Nonetheless, the belt system is highly effective in an emergency because the retractor automatically locks when the belt is rapidly accelerated.